"The US government should be the champion for the internet, not a threat. They need to be much more transparent about what they're doing, or otherwise people will believe the worst.

"I've called President Obama to express my frustration over the damage the government is creating for all of our future. Unfortunately, it seems like it will take a very long time for true full reform."

The NSA (above) and the UK's GCHQ have both been implicated in the scandal

The 29-year-old's call to the most powerful man in the world follows claims on Wednesday that the US National Security Agency "impersonated" Facebook pages so it could spy on computers and access data.

The NSA has called the reports "inaccurate".

It comes off the back of months of further claims of spying, made by whistleblower and former NSA contractor Edward Snowden.

"As the world becomes more complex and governments everywhere struggle, trust in the internet is more important today than ever," writes Mr Zuckerberg.

He adds: "When our engineers work tirelessly to improve security, we imagine we're protecting you against criminals, not our own government.

Wanted: Snowden has temporary asylum in Russia

"The US government should be the champion for the internet, not a threat. They need to be much more transparent about what they're doing, or otherwise people will believe the worst."

A White House official confirmed the two men had spoken on Wednesday: "The President spoke last night with Mark Zuckerberg about recent reports in the press about alleged activities by the US intelligence community."

Facebook began encrypting its pages last year to make the site - which now has 1.2 billion users - more secure.

Yahoo and Google have also allegedly been targets of US and UK intelligence services, with spies accused of secretly intercepting user data without the companies' knowledge.